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Algebra Difficulty 1.6 Junior Find the answer Canada

The first two hours of Melanie’s trip was spent travelling at
$100 \text{ km/h}$ . The remaining
$200 \text{ km}$ of Melanie’s trip
was spent travelling at $80 $\text{}$
km/h}$. Melanie’s average speed during this trip is closest
to

Pick one

Solution

Since each unshaded section is $3$ times the size of each shaded section,
then together the size of $3$ shaded
sections is equal to the size of $1$
unshaded section.

Thus, the combined size of all sections is equal to $12+1=13$ unshaded sections.

We can now imagine the spinner as having $13$ equal sized sections of which $1$ is shaded.

The probability that the arrow stops in a shaded section is equal to the
fraction of the spinner’s area comprised of shaded sections, which is
$\frac{1}{13}$ .

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Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project.